Learning mathematics involves a progression to higher and higher concepts, building on the foundations of what we have already learnt. But Andrew Irving and Ebrahim Patel explain that no matter how high your mathematical knowledge reaches you must never lose sight of your foundations, no matter how basic they may seem.

How does a computer understand the colours to be displayed on the monitor's screen? It's all about red, green and blue and numbers written in a special way.

The Plus anniversary year — A word from the editors